This invention relates to an antistatic layer for a plastic film, particularly to a light-sensitive silver halide photographic material excellent in antistatic ability.
Generally speaking, plastic films have strong chargeability, which gives many restrictions in uses in many examples. For example, in light-sensitive silver halide photographic materials, supports such as polyethylene terephthalate have been generally used, which are liable to be charged particularly at lower humidity during winter season. In recent days, when high sensitivity photographic emulsions are coated at high speed, or light-sensitive materials of high sensitivity are subjected to exposure treatment through an automatic printer, antistatic countermeasures are particularly important.
When a light-sensitive material is charged, static marks may appear by its discharging, or a foreign matter such as dust may be attached, whereby pinholes may be generated to deteriorate quality markedly and workability is lowered extremely for correction thereof. For this reason, surfactants or polymeric compounds containing polyethylene oxide groups, polymers containing sulfonic acid or phosphoric acid groups in the molecule have been employed.
Particularly, chargeability control with a fluorine-containing surfactant or conductivity improvement with a conductive polymer has been frequently used and, for example, in Japanese Unexamined Patent Publications No. 91165/1974 and No. 121523/1974, examples of applying an ion type polymer having dissociable group in the polymer main chain are disclosed.
However, in these prior art techniques, the antistatic ability will be deteriorated to a great extent by developing processing. This may be considered to be due to the fact that the antistatic ability is lost via the steps such as the developing step using an alkali, the acidic fixing step and the step of washing. Therefore, in the case when printing is conducted by further using a treated film as in a printing light-sensitive material, the problems such as pinhole generation by attachment of dust will ensue. For this reason, for example, in Japanese Unexamined Patent Publications No. 84658/1980 and No. 174542/1986, antistatic layers comprising a water-soluble conductive polymer having carboxyl groups, a hydrophobic polymer having carboxyl groups and a polyfunctional aziridine have been proposed. According to this method, antistatic ability can remain after the treatment, but since transparency of the coated film depends greatly on the drying speed, there was involved the drawback that transparency was lowered to a level which could not stand use at all when drying was effected quickly for improvement of production efficiency, even though it might be transparent when drying was effected slowly.